(1) Field of the Invention
The present invention relates to a power generation system in a fuel cell which is applicable as a power generation system in which the main power generation system is a high-temperature solid electrolyte type fuel cell having a preheater for air used in a fuel cell reaction.
(2) Description of the Prior Art
FIG. 1 shows the constitution of a conventional power generation system in a fuel cell, wherein reference numeral 1 is a high-temperature solid electrolyte type fuel cell, numeral 3 is an air preheater, 4 is a waste heat recovery boiler, 5 is an economizer, 6 is a portion in which a high-temperature exhaust gas for a bottoming cycle is recovered, 7 is an afterburner, 8 is a preheater for a fuel gas, 9 is a fuel gas, and 10 is air for a fuel cell reaction.
An operative temperature of the high-temperature solid electrolyte type fuel cell 1 in the above mentioned fuel cell system is as high as about 1,000.degree. C., and the air 10 for the reaction also has the role of cooling the fuel cell. Consequently, a tremendous amount of reaction air having the high temperature is required (see Takehiko Takahashi, "Fuel Cell", Kyoritsu Shuppan, 1984, April, p. 123).
In the power generation system in the fuel cell just described, a high-temperature and high-flow rate type mechanism is required to preheat air 10 for the reaction which will be fed to high-temperature solid electrolyte type fuel cell 1. However, in the case that the preheating is carried out by means of afterburner 7 as in FIG. 1, it is necessary to dispose large-scale afterburner 7, so that the pressure loss of the latter tends to increase. In addition, installation of such a large afterburner is inconvenient from the viewpoint of economy.
New heat exchangers which are made from ceramic materials and which make use of heat pipes have been developed, but at present, such are still technically unsatisfactory.